Safety vent and filler cap for vehicle gasoline tank



Sept- 9, 1969 R. l. FLEMING ETAL SAFETY VENT AND FILLER CAP FOR VEHICLEGASOLINE TANK Original Filed Dec.

United States Patent O U.S. Cl. 220-89 5 Claims ABSTRACT OF THEDISCLOSURE A thin annular band of fusible alloy joins a body member to athreaded ring element, and the latter is threadedly engaged with atubular member communicating with the interior of a fuel tank. When thetemperature of the fusible alloy reaches its melting point, the bodymember may separate axially from the ring element to permit venting ofthe tank to atmosphere.

This application is a division of our copending application Ser. No.598,652 led Dec. 2, 1966, now Patent No. 3,385,468 granted May 28, 1968.That application was a continuation-in-part of our copending applicationSer. No. 472,268 led July l5, 1965.

This invention relates to gasoline tanks of the type used on trucks orother vehicles as a fuel supply to an internal combustion engine, andthis invention is particularly directed to improvements in the vent andfiller cap assemblies lfor such a tank.

Gasoline tanks of the type used on trucks require a vent which willprevent dangerous build-up of pressure within the tank where ambienttemperature, radiant heat, engine heat, road heat, mufer heat, etc. oragitation or surge may cause increase in pressure within the tank. It isalso highly desirable to provide a means for closing olf the vent in theevent that the truck and tank should overturn, in order to preventescape of the gasoline with attendant fire hazard. These tworequirements may be met by providing a vent opening equipped with a ballcheck valve arranged so that overturning of the tank results in seatingof the ball by gravity to close ot the vent passage. However, theprovision of such a gravity-operated check valve gives rise to anotherproblem because motion of the tank contents brought about by motion ofthe truck and tank over the road may cause the ball valve to closeagainst the valve seat and thus block ol the vent, and pressure withinthe tank may then serve to hold the ball valve in closed position. Also,the ball may stick on the seat. It is known that pressure within thetank may build up to a degree which will interfere with proper operationof the engine. A vent opening of adequate size will however permitescape of fuel due to surging.

It is the principal object of this invention to provide a novel yform ofvent device for a vehicle gasoline tank, which vent device remains openduring normal operation, which will close in the event of overturn, andyet which cannot become accidentally closed by surging due to motion ofthe tank.

Another important object is to provide a novel form of surge preventerfor the vent assembly, which is effective to prevent escape of fuel fromthe tank while providing adequate normal venting.

Another object is to provide a novel form of safety device in the ventassembly and in the filler tube closure cap, both of which act to bypassthe vent passages and provide 3,465,912 Patented Sept. 9, 1969 ice muchlarger vent openings into the tank in the event of overheating.

Briefly stated, these objects of the invention are achieved by providinga vented chamber having a separate inlet and outlet each communicatingwith the tank through separate check valves. The inlet to the chamberhas a novel form of guide for a gravity ball which closes against itsseat upon overturning, which guide is constructed so as to prevent theball from being raised by motion of the tank contents into contact withthe valve seat. Although the valve in the outlet may close as a resultof such motion, the valve is promptly opened again by the hydraulic headof liquid fuel in the vent chamber and outlet passage. The valved outletfrom the vent chamber to the tank insures return of fuel from thechamber to the tank, since the outlet has a greater flow capacity thanthe inlet. Liquid fuel may drain back from the chamber through theoutlet while vapor and bubbles ow into the chamber through the inlet.The safety provision for providing large vent openings bypassing thecheck valves in the event of overheating is accomplished by use of a lowmelting, fusible alloy in a novel manner so that the vent valve parts orthe iiller pipe cap or both are separated from the tank when thetemperature of the fusible alloy reaches its melting point.

Other and more detailed objects and advantages will appear hereinafter.

In the drawings:

FIGURE 1 is a sectional view showing a preferred ernbodiment of thisinvention.

FIGURE 2 is a transverse sectional View taken substantially on lines 2-2as shown in FIGURE 1.

FIGURE 3 is a sectional view similar to FIGURE 1, showing amodification.

Referring to the drawings, a gasoline tank generally designated 10 isformed of metal and is adapted to be mounted on a vehicle such as amotor truck. The gasoline is delivered to the internal combustion engineof the truck though conventional means, not shown. A vent valve assemblygenerally designated 11 is mounted on the tank 10 at the highestelevation thereon. This assembly 11 includes a tubular member or sleeve12 extending into the interior of the tank 10. The ring or sleeve isinternally threaded at 13 to receive an externally threaded body memberor bushing 14. This bushing 14 includes the shell 15, the valve seatmember 16 and the thin annular band 17 of fusible alloy joining themtogether. The valve seat member 16 has an inlet passage 18 and aparallel outlet passage 19, both extending therethrough andcommunicating with the chamber 20.

In the form of the invention shown in FIGURE 1, the lower end 22 of thebore 18 is shaped to receive the helical convolutions of the upper endof the coil spring 21 which extends downward into the interior of thetank 10. The member 16 is provided with a downward facing tapered seat23 above the upper end of the spring 21. A ball 24, movable freelythrough the interior of the spring 21, is adapted to engage the seat 23by gravity in the event of overturn of the truck and tank 10. A closure25 is provided at the lower end of the spring 21. The spaces between thespring convolutions serve as lateral port means connecting the inlet 18with the interior of the tank 10.

During operation over the road, the truck and tank may have motionswhich produce surging of the gasoline 26 within the tank and whichmotions might lift the ball to engage the seat but the same motionscause the coil spring 21 to ex in iirst one direction and then theother, with the maximum extent of swinging motion at the lower end ofthe spring 21. This swinging motion of the spring 21 causes the ball 24to remain against the closure 25 by centrifugal force and prevents theball from traveling up the interior ofthe spring to reach the seat 23.

A cap 30 has an internally threaded skirt 31 engaging the externalthreads on the member 16. A circular baiie 32 has its outer peripheryclamped between the cap 30 and the member 16 and is provided with acentral aperture 33.'The space 34 between the bafiie 32 and the cap 30is vented to atmosphere through internal slots 34a which interrupt theinternal threads of the skirt 31 and which extend into communicationwith the space 34.

A porous plug 35 of sintered metal is positioned in the vent chamber 20and has a portion extending into the inlet 18. Liquid passing from theinterior of the tank into the chamber must pass through the pores of theplug 35. A similar porous plug 36 having less resistance to flow thanthe plug is fixed in the upper end of the tube 37 mounted in the outlet19. The lower end of this tube extends into the interior of the tank andis provided with a check valve 38 which closes against a seat 39 whenthe tank-is in inverted position. The ball 38 may also close against theseat 39 by surge action of the fuel in the tank, but it opens again byhydraulic head action of the liquid fuel in tube 37. The liquid passingfrom the chamber 20 into the interior of the tank 10 must pass throughthe pores of the plug 36. In normal operation, gasoline which reachesthe vent chamber 20 from the interior of the tank 10 through the inlet18 does not remain in the chamber 20 because the outlet 1'9 has agreater iiow capacity than the inlet 18 by reason of the greaterporosity of the plug 36 and the tube is longer allowing better flow headpressure.

A tubular member or filler pipe extends into the interior of the tankfor a short distance, the lower end determining the normal maximum levelof gasoline in the tank. Thus, when the usual ller nozzle, not shown, isintroduced into the pipe 50 in the absence of the cap 51, the escape ofair from the tank as it fills with gasoline is very substantiallyreduced when the lower end of the pipe 50 becomes submerged in gasoline.The orifices are still small enough to limit air flow out of tank duringfilling, causing indication through the filler opening that the tank isfull. While it is possible to force fill the tank to a higher elevation,it is desirable not to do so in order to leave adequate expansion space49 within the tank above the level of the gasoline 26.

The cap 51 for the filler pipe 50 includes a body member having a skirt52 encircling an internally threaded ring 53. A thin annular band 54 offusible alloy joins the skirt 52 to the ring 53. The band of fusiblealloy is preferably Woods metal which melts at about 160 F. The radialthickness of the band 54 is uniform and is preferably very thin, forexample, from 0.005 inch to 0.050 inch for a cap of two-inch normalsize. The parts of the cap 51 including the ring 53 are preferablyformed of brass for its high thermal conductivity as well ascorrosion-resistance and non-sparking properties. The fact that thefusible alloy band 54 is very thin provides maximum protection againstaccidental melting brought about by the high specific heat value of thefusible alloy. The thin fusible band gives up its heat readily to thebonded brass parts. The fusible band 54 also provides a very highstrength connection between the parts 52 and 53 as well as affordingmaximum fire vent area. In practice we prefer to make the radial wallthickness of the band 54 thinnest at its upper blind end 55 while theremainder is somewhat thicker, but not greater than 0.050 inch. Thisdifference in radial thickness is achieved by means of a step bore 56 inthe skirt 52 of the filler cap 51. The thinnest section 55 is providedfor manufacturing reasons in order to minimize fiow of liquid alloybetween the upper end of the ring 53 and the under surface 57 of thefiller cap 51.

In operation, the tank 10 is filled with gasoline 26 through `the fillerpipe 50, after first removing the filler pipe cap 51. When the upperlevel of gasoline rises within the tank sufiiciently to submerge thelower end of the filler pipe 50, air from the tank can no longer bedisplaced out through the fillet' pipe 50, and must pass through therestrictions of the porous plugs 35 and 36, and this causes the fillerpipe itself to begin to lill. The filling operation is then terminatedand the filler pipe cap 51 is installed in place. Vapor accumulates inthe expansion space 49 above the level of gasoline 26. This vapor isvented to the atmosphere through the space between the coils of thespring 21 through the seat 23, inlet 18, and chamber 20. Vapor is alsovented through tube 37 to the chamber 20. The chamber 20 is vented toatmosphere through aperture 33, space 34 and passage slots 34a. In theevent that the tank should be force filled above the level of the lowerend of the filler pipe 50, the opening 59 in the sleeve 11 provides forventing of the tank through inlet 18 and chamber 20. The configurationof the cap 30, baie 32 and slots 34a provide a fiame arresting structurefor the whole assembly.

In the event that the vehicle and tank 10 should overturn, the ball 24closes against the seat 23 and the ball 38 closes against the seat 39 toprevent escape of gasoline 26 from tank 10. However, accidental liftingof the ball 24 into contact with the seat 23 while the vehicle is inmotion over the road, where it might be held by vapor pressure, isprevented because the swinging movement of the lower end of the tiexiblec-oil spring 21 holds the ball against the closure 25 by centrifugalforce. Even though the valve 38 might be closed against the motion ofthe seat 39 by motion of the tank or its contents, the ball 24 does notclose against the seat 23. Gasoline which passes through inlet 1S intothe vent cham-ber 20 by surge action escapes from the chamber 20 throughthe outlet tube 37, the hydraulic head acting to move the ball 38downward away from the seat. Since the pores of the plug 36 are lessrestrictive than those of the plug 35, any gasoline which enters thechamber 20 through the inlet can drain back to the tank through theoutlet.

It will be observed that the vent device just described may be placed atany convenient location along the top of the gasoline tank, and need notbe restricted to a position midway between the ends of the tank tominimize surge effects. Tests have shown that the vent device may beplaced at the forward end of the tank at the top and that no leakageoccurs even when the truck is stopped suddenly to develop maximumendwise surge within the tank.

Should the tank or its contents become overheated for any reason, theannular band 54 of fusible alloy melts, and the filler pipe cap 51 isblown ofi by pressure within the tank before the pressure can reach thedangerous intensity. The annular band 17 of low melting alloy whichforms a part of the bushing 16 functions in the same manner. Both ofthese fusible bands 54 and 17 provide a high strength, economicalconstruction, with maximum vent area. Tank pressures are relieved beforereaching dangerous intensities.

In the modified form of the invention shown in FIG- URE 3 the spring 21is replaced by a tube 61. This tube 61 is fixed near its upper end tothe bore 62 of the bushing 16a and the valve seat 23a is convenientlyfixed in the upper end of the tube 61. Vent ports 63 are provided in thewall of the tube 61 below the bushing 16a. A series of lateralindentations 64 are provided in the wall of the tube 61. Theseindentations 64 serve toimpede upward progress of the ball 24 toward theseat 23a brought about by motion of the truck over the road.

The other parts of the apparatus shown in FIGURE 3 have the sameconstruction and operate in the same manner as previously described.

We claim:

1. In a vehicle gasoline tank assembly, the combination of: a tank, aninternally threaded sleeve secured to the upper portion of the tank andcommunicating with the interior thereof, a bushing having a portionextending into said sleeve, said bushing having an externally threadedring element engaged with the threaded sleeve and having a thin annularband of fusible alloy joining said ring element to said portion of thebushing, said annular band melting upon reaching a predeterminedtemperature to permit axial separation of the bushing portion from thering element and venting of the tank to atmosphere.

2. In a vehicle gasoline tank assembly, the combination of: a tank, anexternally threaded filler pipe secured to the upper portion of the tankand communicating with the interior thereof, a pipe cap having a portionencircling the upper end of said ller pipe, said pipe cap having aninternally threaded ring element engaged with the threaded ller pipe andhaving a thin annular band of fusible alloy joining said ring element tosaid portion of the pipe cap, said annular band melting upon reaching apredetermined temperature to permit axial separation of the pipe capportion from the ring element and venting of the tank to atmosphere.

3. In a vehicle gas tank assembly, the combination of: a. tank, athreaded tubular member secured to the upper portion of the tank andcommunicating with the interior thereof, a body member having a portionpositioned concentrically with respect to said tubular member and havinga threaded ring element engaged with the threaded tubular member, thebody member having a thin annular band of fusible alloy joining saidportion of the body member and said ring element, said annular bandmelting upon reaching a predetermined temperature to permit axialseparation of the body member portion from the ring element and ventingof the tank to atmosphere.

4. The combination set forth in claim 3 in which said tubular member isan internally threaded sleeve, said ring element ybeing externallythreaded, and said annular band being positioned within said ringelement.

5. The combination set forth in claim 3 in which said tubular member isan externally threaded filler pipe, said ring element being internallythreaded, and said annular band encircling said ring element.

References Cited UNITED STATES PATENTS 166,452 8/ 1875 Brown et al.1,142,902 6/1915 McNutt. 1,953,582 4/ 1934 Belknap 169--42 2,357,620 9/1944 Thomas.

RAPHAEL MSCHWARTZ, Primary Examiner

